Cancer blood test may change face of treatment, help extend lives

A blood test to see how well women respond to breast cancer treatment could be available in Britain in two years, according to scientists behind the innovation.

The test, which looks for free-floating DNA from tumours, could help patients live longer by identifying much sooner when a drug is not working.

Prof Carlos Caldas, of Cancer Research UK’s Cambridge Institute, described the test as a “liquid biopsy” which might eliminate the need for many invasive and potentially dangerous tumour biopsies in years to come.

Women treated with radiation for breast cancer are more likely to develop heart problems later, even with the lower doses used today, troubling new research suggests. The risk comes from any amount of radiation, starts five years after treatment and lasts for decades, doctors found.

Patients shouldn’t panic — radiation has improved cancer survival, and that is the top priority, doctors say. The chance of suffering a radiation-induced heart problem is fairly small.

For example, four to five of every 100 women who are 50 years old and free of heart risks will develop a major cardiac problem by age 80, and radiation treatment would add one more case, the research suggests.

He said the test was much cheaper than existing ones, which looked for whole tumour cells in the blood, and could cost just “tens of pounds”.

He explained that blood was tested for free-floating DNA, which identifies tumours just as bar codes identify products.

This meant genetic changes signalling growing resistance could be picked up months earlier than the current method, in which CAT scans are given to spot physical tumour growths.

When new tumours are spotted, patients are switched to alternative drugs. Prof Caldas said: “In about 50% of patients, we could detect that they were not responding to treatment about five months before the CAT scans.”

He emphasized it was still “early days” with the techniques and that the study, published in the New England Journal of Medicine, had been of only 30 patients.

‘My expectation is that this test will be routine practice in two to three years’

Larger trials are under way to validate the test and see if it can help patients live longer.

Prof Caldas added: “My expectation is that this test will be routine practice in the NHS in two to three years, for people with advanced cancer.”

He noted that the test could eventually be used for a range of cancers, not just breast cancer.

It might also be able to spot whether cancers are returning, but he said that was a question for a later date.